IPv6 security for sites
(based on my GridKa School talk)
David Kelsey (STFC-RAL)
HEPiX IPv6 WG, CERN
16 Sep 2015
IPv6 security pros/cons
• Advantages of a new design
– Security: important part of the IPv6 initial design
• Down-sides
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Lack of maturity
New vulnerabilities and attack vectors
Need IPv6-compliant monitoring and tools
Lack of education and experience
Problems of transition – dual-stack, tunnels
• BUT - Many threats/attacks happen at layers above/below the
network layer
– And are therefore exactly the same as in IPv4
– Malware, phishing, buffer overflows, cross-site scripting, DDoS etc etc
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Immediate IPv6 concerns
• IPv6 may be on by default (and not controlled or monitored)
• End systems have multiple addresses
• Searching logs will not always work
– Formatting when writing the logs is still broken
– Same address but different formats (drop zero or not)
• What is wrong with tunnels?
– Site may not be in control
– Tunnels traverse the IPv4 perimeter firewall and NAT gateways
• Reputation-based (IP address) web protection does not fully
exist for IPv6
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IPsec
• Was first developed in 1995 for IPv4 internet layer
– SSL and TLS operate at Application Layer
• A framework of standards
– End to end authentication, data integrity and privacy (encryption)
• Can be used site to site (gateway to gateway)
– As a Virtual Private Network (VPN)
• Or host to host
• All major aspects are same in IPv6 as IPv4
• Does not fully support protection for multicast traffic
– Key management is one-to-one
• No longer mandatory (rfc6434 – MUST -> SHOULD)
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IPv6 problems in IPv4-only world
• Turned on by default on many Operating
Systems
– Windows Vista was the first
• Rogue router advertisements
– Badly configured or malicious
• Tunnels turned on (by default, by bad config.)
• IPv6 and tunnels can bypass firewalls
– Must filter IPv6 traffic and tunnels
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IPv6 deployment risks
• The attacker community can make good use of IPv6
– They are IPv6 experts
– E.g. for tunneling leaked info out from compromised systems
• Vulnerabilities present in IPv6, including day zero issues
inherent in any new or revised system
– 224 CVE entries with keyword “IPv6” since 2002
– 29 in 2015
• Complexity added by dual IPv4/IPv6 operations
• Immaturity of IPv6 security products and processes
• Lack of vendor support.
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NAT and IPv6
• NAT has been essential to preserve the IPv4 address
space
• Many concerns about lack of NAT in IPv6
• IPv4 address/port translation is not the main
protection of the end systems
• It is the stateful firewall that protects!
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Some IPv6 protocol attacks
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Extension Header vulnerabilities
• Routing Header Type 0
– Source Routing
• Lots of security issues with RH0
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Destination address in packet is replaced at every Layer 3 hop
Difficult for firewalls to determine the actual destination and compare with policy
Can be used for DoS traffic amplification
RH0 depracated (rfc5095)
• Fragmentation issues
– Upper-layer info may be in second packet (and not inspected by firewall)
– IPv6 standard defines every link to have MTU of at least 1280 bytes
• Smaller fragments should be suspicious
• Hop-by-hop extension header also dangerous
• Solutions include
– Filter on allowed and expected EH
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Newer RFCs on Headers
• rfc6564 - A Uniform Format for IPv6 Extension
Headers (April 2012)
• rfc7045 - Transmission and Processing of IPv6
Extension Headers (Dec 2013 – B Carpenter)
• rfc7112 - Implications of Oversized IPv6
Header Chains (Jan 2014)
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Neighbor Discovery Protocol
• NDP authenticates neither the requestor or responder
– Spoofing is possible
• SLAAC, NDP and DAD include protection mechanisms
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Source address for RA and NS messages must be unspecified (::)
Hop limit must be 255 (the maximum)
RA and NA messages must be rejected if hop limit is not 255
This prevents a remote attacker sending forged RA or NA messages
• scope is always local
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Secure Neighbor Discovery
• Secure Neighbor Discovery (SEND) (rfc3971)
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Uses Cryptographically Generated Addresses (rfc3972)
SEND has a pair of public/private keys per IPv6 node
ND is extended with more options
Interface identifier is crypto generated based on current IPv6
prefix/public key
– Signatures are generated and checked to authenticate nodes
• Not many implementations
• How are keys generated/managed?
• How many actually use this?
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Rogue RA
• No authentication mechanism built into SLAAC
• Malicious host can send rogue RA and pretend to be a router
– Can capture or drop packets
• Badly configured systems too
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Detecting rogue RA messages
• Use generic IDS with customised signatures
– RA whose source MAC or IP is not in a configured list
• Lots of manual configuration!
• Use tool NDPMon
– And check against XML config file
– also monitor all NS and NA
– To check when NA contradicts a previous one
• Intelligent switches – known RA source
• Cisco RA Guard
• Rafixd (and ramond)
– Detect all rogue RA messages and immediately transmit another
forged RA with lifetime 0 seconds (to clear the rogue info on all nodes)
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DAD
• Duplicate Address Detection
– Host checks whether its address is already in use
– Sends NS asking for resolution of its own address
– An attacker can launch a DoS attack by pretending
to own all IPv6 addresses on the LAN
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ICMPv6
• Internet Control Message Protocol (rfc4443)
• An important component of IPv6
• Redefines ICMPv4 with additions and changes
– Ping, destination unreachable, neighbor discovery, path MTU discovery
– Error messages (message number 1 to 127)
– Informational messages (128 to 255)
• Essential to establish strict ICMP filtering policies
– Define ICMPv6 messages that can/cannot pass between the site and the
internet
• E.g. PMTU and ND
• Rfc4890 “Recommendation for Filtering ICMPv6 Messages in Firewalls”
– Each site needs to consider carefully!
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Issues for Sites
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NIST 800-119 quote
• The deployment of IPv6 reinforces the basic security
lessons learned with IPv4. These security practices
include defense in depth, diversity, patching,
configuration management, access control, and
system and network administrator best practices.
Good security practices remain unchanged with the
deployment of IPv6. Good security practices will
reduce exposure and recovery time in case of a
security event.
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Critical Security Controls for
Effective Cyber Defense
http://www.sans.org/critical-security-controls/ (© SANS, CC-BY-ND)
Top 20 Critical Security Controls (Version 5)
1: Inventory of Authorized and Unauthorized Devices
2: Inventory of Authorized and Unauthorized Software
3: Secure Configurations for Hardware and Software
on Mobile Devices, Laptops, Workstations, and
Servers
4: Continuous Vulnerability Assessment and
Remediation
5: Malware Defenses
6: Application Software Security
7: Wireless Access Control
8: Data Recovery Capability
9: Security Skills Assessment and Appropriate Training
to Fill Gaps
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10: Secure Configurations for Network Devices such as
Firewalls, Routers, and Switches
11: Limitation and Control of Network Ports, Protocols,
and Services
12: Controlled Use of Administrative Privileges
13: Boundary Defense
14: Maintenance, Monitoring, and Analysis of Audit Logs
15: Controlled Access Based on the Need to Know
16: Account Monitoring and Control
17: Data Protection
18: Incident Response and Management
19: Secure Network Engineering
20: Penetration Tests and Red Team Exercises
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ISSeG: Top 12 Recommendations
EU FP6 Project – partners: CERN, FZK (now KIT), STFC
(Integrated Site Security for Grids)
http://isseg-training.web.cern.ch/ISSeG-training/Recommendations/Top-Recommendations.htm
R0 : Perform a site security risk assessment
R1 : Create and review your information security policy
R8 : Encourage information security awareness, education and training
R14 : Separate your development, test, and operational facilities
R16 : Install and regularly update malicious code detection and repair software for example anti-virus
R18 : Establish backup and restore policies and procedures
R23 : Enable audit logging of user activities, exceptions and security events
R26 : Restrict and control the allocation of privileges
R28 : Enforce good practices in the selection and use of passwords
R29 : Ensure that unattended equipment is appropriately protected
R36 : Establish a CSIRT and incident response procedures
R39 : Protect your confidential and sensitive data
Copyright (c) Members of the ISSeG Collaboration 2008
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UK Jisc advice
• Technical Security for e-Infrastructures (Nov
2014)
• Considers the Cyber-Security Council’s Top 20
controls
• General, not IPv6
• https://community.jisc.ac.uk/groups/uk-einfrastructure-security-access-managementwg/
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IPv6 issues for
security/network teams
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Control IPv6 if not using it
Use Dual-stack and avoid use of tunnels wherever possible
Drop packets containing RH Type 0 and unknown option headers
Deny packets that do not follow rules for extension headers
Filter IPv6 packets that enter and leave your network
Restrict who can send messages to multicast group addresses
Create an Address management plan
Create a Security Policy for IPv6 (same as IPv4)
Block unnecessary ICMPv6
Protect against LAN RA, ND and DHCP attacks
– Use SEND and authenticated DHCPv6 (is this useful?)
– NDPMON and RAFIXD on critical segments
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Check/modify all security monitoring, logging and parsing tools
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Issues for Sys Admins
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IPv6 issues for sys admins
• Follow best practice security guidance
– System hardening as in IPv4, see for example
– https://access.redhat.com/documentation/enUS/Red_Hat_Enterprise_Linux/6/pdf/Security_Guide/Red_Hat_Enterprise_Linu
x-6-Security_Guide-en-US.pdf
– Specific advice on IPv6 hardening, see for example
– https://www.ernw.de/download/ERNW_Guide_to_Securely_Configure_Linux_
Servers_For_IPv6_v1_0.pdf
• Check for processes listening on open ports
– # netstat, lsof
• Review neighbour cache for unauthorised systems
– # ip -6 neigh show
• Check for undesired tunnel interfaces
– # ip -6 tunnel show, # route
–A inet6
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Sys admins (2)
• Ensure not unintentionally forwarding IPv6 packets
– /proc/sys/net/ipv6/conf/*/forwarding files
– Or net.ipv6.conf.*.forwarding sysctl
• Use OS embedded IPv6 capable stateful firewall
– filter based on EH and ICMPv6 message type
• Ip6tables (can we provide advice?)
• IPv6 aware intrusion detection
– E.g. Snort, Suricata, Bro
– https://www.sans.org/reading-room/whitepapers/detection/ipv6open-source-ids-35957
• Use IPsec between critical servers to secure communications?
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More Information?
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More information
• Many IETF RFC documents on IPv6
– Especially RFC4942 (IPv6 Transition/Coexistence Security Considerations)
• IPv6 Security – Protection measures for the next Internet
Protocol, Scott Hogg and Eric Vyncke, Cisco Press (2009)
• NIST Guidelines for the Security Deployment of IPv6 (NIST
SP800-119)
http://csrc.nist.gov/publications/nistpubs/800-119/sp800-119.pdf
• Internet Society – top 10 IPv6 security myths
https://www.internetsociety.org/deploy360/blog/tag/ipv6-security-myths/
• Operational Security Considerations for IPv6 Networks (Sep
2015!)
https://tools.ietf.org/html/draft-ietf-opsec-v6-07
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Questions?
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